FIGS. 9 and 10 are a vertical cross-sectional view and a side view showing the concept of an expansion valve 10 of the prior art. In FIG. 9, the inner structure is omitted. A substantially rectangular solid-shaped valve body 30 of a thermal expansion valve comprises a refrigerant path 11 of a refrigeration cycle, and a first path 32 through the valve body 30 which extends from a refrigerant exit of a receiver 6 (which is preceded in the refrigerant path 11 by a condenser 5) to a refrigerant entrance of an evaporator 8, and a second path 34 through the valve body 30 which extends from a refrigerant exit of the evaporator 8 to a refrigerant entrance of a compressor 4 which is in the refrigerant path 11. The first path 32 and the second path 34 are formed so that one path is on top of the other path with a distance in between.
A valve hole 32a is formed in the first path 32 for the adiabatic expansion of a liquid refrigerant supplied from the refrigerant exit of the receiver 6. The valve hole 32a has a center line along a longitudinal direction of the valve body 30. A valve seat is formed in the entrance of the valve hole 32a. A valve member 32b is supported by a support member 32d in the valve seat, and is biased with the supporting member 32d by a biasing means 32c, for example a compression coil spring or the like.
The first path 32 comprises an entrance port 321 to which the liquid refrigerant from the receiver 6 is introduced and an exit port 322 for supplying the refrigerant to the evaporator 8. The valve body 30 includes the entrance port 321 and a valve chamber 35 connected to the entrance port 321. The valve chamber 35 is a chamber with a bottom formed on the same axis as a center line of the valve hole 32a, and is sealed by a plug 37.
On the upper end of the valve body 30, a valve member driving device 36, which comprises a heat sensing portion for driving the valve member 32b, is mounted by a screw. The valve member driving device 36 has a pressure activation housing 36d whose inner space is divided into an upper pressure activation chamber 36b and a lower pressure activation chamber 36c by a diaphragm 36a.
The lower pressure activation chamber 36c inside the pressure activation housing 36d is connected to the second path 34 through a pressure hole 36e formed in a concentric manner with the center line of the valve hole 32a.
A vaporized refrigerant passing through the evaporator 8 enters the second path 34 from the refrigerant exit. The path 34 is a path for gas-phase refrigerant, wherein the pressure of the vaporized refrigerant enters the lower pressure activation chamber 36c through the pressure hole 36e.
A valve member driving shaft 36f penetrating the second path 34, and extending from a lower surface of the diaphragm 36a to the valve hole 32a in the first path 32, is positioned in a concentric manner with the pressure hole 36e. The valve member driving shaft 36f comprises on its upper end a stopper portion 36fl which contacts the lower surface of the diaphragm, and is supported so as to be able to slide upward and downward along an inner surface of the lower pressure activation chamber 36c of the pressure activation housing 36d and along a wall which separates the first path 32 and the second path 34 in the valve body 30. The lower end of the valve member driving shaft 36f contacts the valve member 32b. In an outer peripheral area of the separation wall which serves as a guide hole for the valve member driving shaft 36f, a sealing member 36g is mounted to prevent leaking of refrigerant from the first path 32 to the second path 34.
The upper pressure activation chamber 36b of the pressure activation housing 36d is filled with a known heat sensing gas for driving diaphragms. The valve member driving shaft 36f is exposed in the pressure hole 36e and in the second path 34 to the temperature of the refrigerant passing through the second path 34 from the evaporator 8 to the compressor 4. The valve member driving shaft 36f acts as the heat sensing shaft and assumes the temperature of the refrigerant passing through the valve. This temperature assumed by the valve member driving shaft 36f is transmitted to the uppermost portion of the shaft 36f, including the stopper 36fl, and therefore to the pressure activation housing 36d. This temperature transmitted to the pressure activation housing 36d causes the gas in the upper pressure activation chamber 36b to expand or contract accordingly. A tube 36h is utilized for filling the upper pressure activation chamber 36b with heat sensing gas, and is closed after the filling.
A diaphragm driving fluid (heat sensing gas) inside the upper pressure activation chamber 36b turns into gas in correspondence with the heat transmitted thereto, and applies pressure to an upper surface of the diaphragm 36a. The diaphragm 36a deforms in the upward or downward direction according to a difference in pressure applied to a top surface of the diaphragm from the upper chamber 36b and pressure applied to the lower surface of the diaphragm 36a.
Displacement of the diaphragm 36a in the upward or downward direction is transmitted to the valve member 32b through the valve member driving shaft 36f, and moves the valve member 32b away from or toward the valve seat of the valve hole 32a, respectively. As a result, the flow of refrigerant passing through the valve hole 32a is controlled.
As is shown in FIG. 10, two bolt holes 50 are formed in the valve body 30. These bolt holes are used to mount the expansion valve and a corresponding member.
The valve body 30 having the above structure is manufactured by extruding aluminum alloy and adding mechanical processing, such as machining, thereto.
The first path 32 has a complex structure including two separate path sections, an orifice, and a valve chamber 35 within the valve body 30. The second path 34 has a simple structure including only a passage for the gas-phase refrigerant to pass from the evaporator 8 to the compressor 4. Therefore, the second path 34 can be processed as a straight penetrating hole.
Further, the two bolt holes 50 need only comprise a simple passage for the bolt to pass through.
The present invention provides an expansion valve whose valve body is manufactured in a simplified manner by using a hollow extrusion processing.